Hi Christophe and Gmsh team,
I've been trying to model a simple cube with a cylindrical hole that is NOT through-going (i.e., its depth is smaller than the depth of the cube), as shown in the attached picture. The Extrude command doesn't seem to work since it will extrude both surfaces (exterior and interior -- hole) at the same time. I know I can define all the surfaces, surface loops, and volumes manually, but is there a better way of defining something like this in Gmsh?

I also tried to use the Compound Volume command by first defining two volumes from Extrude and then trying to combine them but I'm getting errors for the Compound Volume visualization (Error: Cannot evaluate bounds on GRegion Compound) and when I mesh the geometry, the actual shared interfaces are still existing, although by the notion of compound from the documentation, the internal interfaces should be neglected. Here is the geometry file:

   // Characteristic length (==> element size)
   cl_external   = 25;
   cl_excavation = 5;

   // External boundaries
   Point(1)      = {-127, 0.0, -127, cl_external};
   Point(2)      = {+127, 0.0, -127, cl_external};
   Point(3)      = {+127, 0.0, +127, cl_external};
   Point(4)      = {-127, 0.0, +127, cl_external};
   Line(1)       = {1, 2};
   Line(2)       = {2, 3};
   Line(3)       = {3, 4};
   Line(4)       = {4, 1};
   Line Loop(1)  = {1, 2, 3, 4};

   // Excavation boundaries
   Point(5)      = {0.0, 0.0, 0.0, cl_excavation};
   Point(6)      = {19.05, 0.0, 0.0, cl_excavation};
   Point(7)      = {0.0, 0.0, 19.05, cl_excavation};
   Point(8)      = {-19.05, 0.0, 0.0, cl_excavation};
   Point(9)      = {0.0, 0.0, -19.05, cl_excavation};
   Circle(5)     = {6, 5, 7};
   Circle(6)     = {7, 5, 8};
   Circle(7)     = {8, 5, 9};
   Circle(8)     = {9, 5, 6};
   Line Loop(2)  = {5, 6, 7, 8};

   //Using compound volumes
   Plane Surface(1) = {1};
   out1[] = Extrude {0.0, 76.2, 0.0}{Surface{1};};

   Plane Surface(2) = {1};
   out2[] = Extrude {0.0, -76.2, 0.0}{Surface{2};};

   Compound Volume(3) = {1, 2};


I also tried to create the geometry in CAD software and imported it as iges, brep or step formats but for reason the hole is not there completely. See for instances the iges file attached.

Can you kindly shed some light here? Am I doing something wrong? Or are there Gmsh tricks/commands that I can use to achieve my goal?

Thank you,
Omid

--
Omid Mahabadi, Ph.D.
Geomechanica, Inc.
http://www.geomechanica.com/
Tel : +1-647-478-9767
Cell: +1-416-824-2408

Attachment: block.iges
Description: IGES model

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